1. Technical Field
The present invention relates to an accumulator-type liquid sprayer, and aims to effectively prevent leakage of the liquid within a cylinder of the sprayer.
2. Prior Art
As a sprayer for spraying finely atomized liquid such as lotion, cologne or perfume, aerosol-type sprayers are widely used wherein dispersed fluid is filled in a container together with pressurizing medium. This type of sprayer is relatively expensive in terms of production cost, and requires discharge of the pressurizing medium by piercing a hole in the container when it is discarded, since in many instance the pressurizing medium remains in the container even after the dispersed fluid has been fully consumed. Thus, the disposition of the container is troublesome, besides that discharge of the pressurizing medium into atmosphere may lead to environmental contamination.
Therefore, it is a recent trend to reevaluate accumulator-type liquid sprayer which does not require pressurizing medium as used in the aerosol-type sprayers, and which sprays the content under an elevated inner pressure obtained by a couple of pumping actions of the discharge head. In this connection, reference may be had to a pump-type sprayer as disclosed in U.S. Pat. No. 5,638,996.
Typically, an accumulator-type liquid sprayer includes a cylinder having a suction port communicating with interior of a container and fixedly held at a mouth portion of the container, a piston arranged in the cylinder, a piston guide for opening or closing a passage for passing therethrough a liquid to be sprayed, by engaging with, or disengaging from the piston, a hollow stem for holding one end of the piston guide and having another end in engagement with a back face of the piston through a resilient member, and a pressurizing cap in engagement with the hollow stem and having a nozzle for discharging the content flowing through an internal passage, wherein the pressurizing cap is repeatedly applied with intermittent load for sucking and pressurizing the content and thereby achieving a pumping action for continuously spraying the content.
In this instance, the piston and the piston guide are sandwiched from both sides and thereby held by resilient means (inner pressure adjusting spring and sucking/pressurizing spring). The force of the resilient means is adjusted so that the piston and the piston guide are in contact with each other when the pressurizing cap is not applied with a load, to thereby close the passage for passing the liquid therethrough.
Incidentally, in order to reduce the load to be applied to the pressurizing cap upon spraying the content and thereby realize spraying under a smooth pumping action, it would be effective to lower the resilient force of either one of the inner pressure adjusting spring and sucking/pressurizing spring, among the resilient means. In this instance, however, since the contact pressure between the piston and the piston guide is reduced, liquid leakage may occur in the cylinder, making it difficult to achieve an efficient spraying of the content.
In the case of accumulator-type liquid sprayer, furthermore, since the piston has a substantially flat end surface, if this flat end surface is brought into contact with a stepped surface provided in the cylinder so as to restrict displacement of the piston within the cylinder, the root portion of the stepped surface may cause deformation or damage of the piston end surface, giving rise to degradation of the tightness in the cylinder or admittance of air, making it difficult to achieve sufficient sealing function.